We all start Penis Enlargement for our own peace of mind. Ultimately, every man has to find his own comfort level with the size of his dick. To me, insanity is the guy who starts at 9.75" (which is larger than 99.9% of the dicks in the dick universe) and wants to add two more inches because his girl said that she had been fucked by a guy with an 11.75" dick, but didn't enjoy it as much as she did with him. But if that is what it takes for him to reach his comfort level with his own dick, far be it for me to say there's something wrong with that. However, it takes more than just a big dick to keep a woman interest in you. Just look at all of the adult entertainment stars and other celebreties that are reported to have big dicks who have gotten divorced (i.e . Tommy Lee, Liam Neeson, John Holmes, Julian, etc). Janice Dickinson (model) openly bragged about the size of Liam Neeson's dick (actor), but you notice that she is not still with him.
Unless you're gay, chances are you will never see another man's dick erect in person. Men don't generally go around showing off their erections. I've never seen another dick bigger than mine in person and I don't really want to (although I've seen many bigger dicks in adult entertainment and even on this site). I've fucked more than my fair share of women and never had any complaints when my dick was 7.5" (although there were some where I felt a bigger dick would have been useful). Currently, I seem to have plateaued at 8" (EL). My ultimate goal is 8.5" (EL). If I don't get there, I won't be disappointed, but I believe I eventually will. My wife is well pleased with my current size.
If you've ever seen the movie The Man from Elysian Fields, there's a lesson to be learned. In the movie, Mick Jaggers spent his whole life learning how to please many women (he was a male escort). In the end he discovered that he only had to find a way to please just one.